The invention is related first to a method for the continuous production, handling, and filling of bags, in particular automatic-machine bags made from a thermoplastic synthetic-resin web having at least one hang-up hole at a filling end, wherein the bags are held together in stacks but are filled and then closed individually.
In the continuous production of bags the bags are brought together by an assembling device in a predetermined number to so-called bag stacks. An input device is formed for example by a horizontally movable pin-type stack conveyor which carries the separated bags on wicket pins. A problem with all the bag-making machines with downstream collecting or stacking devices is matching the throughput capacity of the stacking and collecting devices to the continuously working bag-welding machine that cycles very quickly during bag manufacture with very small pauses while finished bags are pulled from the stacking station and an empty stacking device is fed into the stacking station. In the production of bag stacks it is known to fix them together with a staple. To this end either the bag stack is lifted from the pins of the pin-type stack conveyor and the stacked but not attached bags are set on the legs of the staple, or the legs of the staple are inserted along grooves in the pins of the pin-type stack conveyor and in this manner the bag stack is transferred. Subsequently the bag stack is secured by washers or plugs fitted to the staple legs. This procedure is usually carried out manually by a worker. Attempts have been made to automate the staple insertion and the bag removal. A transfer device of this type is seen for example in German 3,834,115.
It is known from practice that the quality of such bags leaves much to be desired in part because packaging such bag stacks is fairly difficult because of the staples. In addition handling in such a system is relatively expensive. Also, the staple must be covered on both sides with paper strips in the box but once un-packed by an automatic machine the staple must be cleared of its washers or plugs so that the bags can be efficiently filled. Finally the staple must be sent back to the manufacture, that is the bag plant, so that it can be used again.
It is an object of the invention to provide a method of the above-described type that ensures simplified handling in the logistical step between the production and filling of bags, in particular automatic-machine bags, made from a thermoplastic synthetic-resin strip as well as to provide a higher-quality stack formed from a plurality of bags. In addition an apparatus should be provided that simply allows an optimal preparation of the bags fed to the bag stack in order to fill them.
This object is attained with respect to the method in that during the production process the stacked bags are blocked together at locations near their fill openings and that in a preliminary station upstream of a filling station of a filling machine the bag stack is held together by a holding element fitting through the hang-up holes and then the bag stack is deblocked, whereupon the separated bags are filled in the filling station with a filling movement stripping the bags from the holding element and finally the bags are closed.
The system according to the invention eliminates the staple by using a relatively easy blocking to simplify the manufacture and production of the bags, in particular automatic-machine bags. Removal of the bag staple by the pin-type conveyor is now therefore substantially simpler. At the same time the quality of the bag stack is substantially improved and backing of the bags in a box is simplified since there is no bothersome staple. In particular the production and further handling of the bags is made cheaper since moving the staple between the unpacker and the manufacturer is eliminated. It is only necessary to hold the bags in a stack together in the unpacking station and to remove the blocking produced during manufacture of the bags in the stack.
Optimal relationships in the work flow are in particular obtained when two blocking regions and two hang-up holes are provided in an upper flap near the fill opening of each bag, a spacing between the limited-area blocking regions being greater than a spacing between the hang-up holes.
In order to simplify subsequent removal of the blocking it is advantageous when the blocking regions are of semicircular shape at an edge of the upper flaps and the semicircular shape of the blocking regions is delimited by a perforation line formed in the bag stack.
In this manner it is possible to remove all the blocking regions delimited by perforation lines for a stack in the preliminary station of the feed machine as an end block. The removal is effected by a shear movement. Alternatively it is possible to effect the removal by cutting the end blocks out of the bag stack.
With respect to the apparatus the idea according to the invention can be effected particularly simply when the apparatus for feeding blocked bag stacks to a filling in station in particular of an automatic filling machine has a bag holding device and an end-block holding device movable relative thereto. The bag holding device and the end-block holding device each have upper and lower clamping members. The upper and lower clamping members of the end-block holding device constituted as openable and closable pincers. A direction of movement of the pincers is generally vertical.